Introduction to Networking for NonStop S-Series Servers

Expand Network
Introduction to Networking for HP NonStop S-Series Servers
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Priority Routing
Priority Routing
You can assign different priorities to messages sent over an Expand network. Priority
routing allows an important message to reach its destination even when the network is
congested.
Fault-Tolerant Operation
Using careful configuration and network-topology design, you can configure an Expand
network to be continuously available.
You can configure as many as eight lines between the same two nodes using the
Expand subsystem’s multiline path feature. The Expand subsystem can
simultaneously transmit data over all of the lines, thus increasing overall bandwidth,
and will automatically reroute data over remaining lines if one or more lines fail.
You can configure as many as 16 paths between the same two nodes using the
Expand multi-CPU feature. The Expand multi-CPU feature enables you to spread the
communications load over multiple processors by connecting multiple Expand line-
handler processes on separate processors at one node to Expand line-handler
processes on separate processors on another node. The Expand subsystem transmits
data between neighbor nodes over all of the paths in a multi-CPU path, and will
automatically reroute data over remaining paths if one or more paths fail. The Expand
subsystem also uses a rebalancing algorithm to ensure that the average
communications load of all the paths in a multi-CPU path is close to equal.
You can also configure lines to be controlled by different communications hardware
devices to ensure that a single hardware failure will not disable a connection between
two servers.
Network Management
Network management involves several tasks, including
•
Monitoring, modifying, and controlling the network
•
Resolving network problems
•
Analyzing and tuning network performance
The Expand subsystem supports a variety of network-management utilities and tools to
help you perform these tasks:
•
Subsystem Control Facility (SCF)
•
Event Management Service (EMS)
•
Availability Statistics and Performance (ASAP)
•
Measure
Note. Refer to the Expand Configuration and Management Manual, for information on manag-
ing Expand using SCF.